In a known inkjet print head, ink is arranged in a pressure chamber. The pressure chamber has an ink inlet at a first side of the pressure chamber and a nozzle at a second side, opposite of the first side. The pressure chamber ends at the nozzle. No ink may flow beyond the nozzle other than by being jetted through the nozzle. So, for example if no ink is jetted, dirt and/or air bubbles may become trapped in the pressure chamber, near the nozzle. With a large amount of dirt or with large air bubbles, or other similar irregularities in the pressure chamber, a droplet ejection may become disturbed or the nozzle may become blocked completely.
In another known inkjet print head, another arrangement of the print head is selected. A continuous flow of ink passes through an ink channel. At a first side of the ink channel, an actuator, for example a piëzo actuator or a heating element for thermal actuation as well known in the art, is arranged opposite a nozzle arranged at a second, opposite side of the ink channel. Due to the continuous flow, there is less chance that an air bubble or dirt becomes trapped near the nozzle as it may flow with the ink through the ink channel towards a central reservoir. In the ink channel, for example in the ink reservoir a filter means may be provided for removing dirt and/or air from the ink coming from the ink channel returning to the reservoir. Thus, air bubble free and dirt free ink may be re-introduced in the ink channel.
A disadvantage of the latter, known print head is the fact that it is not suited to be used in combination with certain inks, for example high viscosity inks, since an actuation efficiency, that is an actuation pressure generated by the actuator, is significantly decreased. More in particular, in the known continuous flow print head, the actuation efficiency is about 50% lower compared to the above first mentioned print head (having the nozzle arranged at an end of the pressure chamber).